Process of making stencils



- P. H. MURPHY PROCESS OF MAKING STENCILS Sept. 11, 1934.-

Filed May 16. 1932 2 Sheets-Sheet 1 FIG. 2.

FIG. 1.

A INVENTVGR. Philip Hliurph Sept. 11, 1 934. p H. MURPHY 1,973,151

PROCESS OF MAKING STENCIL-S v Filed May '16. 1932 2 Sheets-Sheet 2 FIG.5.

Philip H. NuPfi- H INVENTOIR.

Z Z22 f ATTORNEYS.

TES

' UNITED STA PATENT OFFICE PROCESS OF MAKING STENCILS Philip H. Murp y,Wisdom, Mont.

Application May 16, 1932, Serial No. 611,683

This invention relates to the art of stencil making and moreparticularly to a process of stencil -making where a heated instrumentis applied to a stencil sheet.

In the past, three major types of stencil sheets have been in use in theUnited States. These are represented first by the early para'flin or waxcoated sheet, second by the later, so-called indestructible stencilsheet having a coating of colloidal proteins, such as gelatin, combinedwith a tempering agent such as sugar or glycerine,

third the modern cellulose ester treated Yoshino paper stencil sheet.The first type was superseded by the second mainly because the parafiinor soft wax coated sheet required extraordinary care in handling, everyminor crease, fold or scratch in the sheet showing up in the printing.However, the second type or gelatin coated sheet was in general use onlyuntil about 1925 principally because it was discovered that the coatinghardened after a comparatively short period and the sheet could then beemployed only after a laborious and somewhat not very effectiveapplication of a moistener to re-soften the coating.

As an example of the modern stencil sheet,

which may be employed in this process, reference is had to United StatesPatent No. 1,526,982, dated February 17, 1925.

However, it should be understood that by the term modern stencil sheet,it is intended to designate a stencil sheet comprising an ink-penetrablebase, coated or impregnated with a heat-resisting ink-impervioussubstance, such as pyroxylin enamel, which will not change itsink-impervious properties during a temperature range of between 100 andSOO Fahrenheit.

Again referring to the first type of stencil sheet, the wax or parafllncoating could be readily melted, since paraffin melts at approximately120 Fahrenheit, so as to produce lines and dots by the use of a heatedstylus, but when a heated instru-' ment was employed which had a largersurface area as, for instance, large face type, the heat melted the waxsurface beyond the edges of the type surface area, since it was foundnecessary to apply the heated instrument for a longer periodthan whenmere lines or dots were required. Often the melted wax would again runinto the de-coated area and render the sheet useless. Instruments heatedto temperatures above 120 Fahrenheit, and particularly temperatures of650 Fahrenheit or thereabout, when brought close to the wax coating, aswhen applying the instrument, melted the coating before the instrumenttouched the same, the melted area extending beyond the area of theheated surface.

As for the second type of stencil sheet, it was discovered that whenapplying a heated instrumentto the gelatin coated sheet, a heat above120 Fahrenheit was required but the de-coated area could notbe'successfully freed of protein residues which interfered withsuccessful printing from such sheet. In addition, the heat necessary wassuch that the base of porous paper 05 charred before the melting wasaccomplished. As a result, the use of heated implements in makingstencils was practically abandoned and the pressure method, employinglines and dots, was substituted; This method called for the use ofconsiderable pressure of the instrument upon the coated surface and itwas soon discovered that only lines and points or dots could beemployed, rendering a solidly inked surface or area impossible. It wasalso discovered that the Japanese 76 Yoshino paper which came intogeneral use as a base for the stencil sheet, did not respond well to theuse of a stylus since the fibers became loosened, were picked-up by thestylus, collected the ink-impervious coating and were hard to 80 removefrom the de-coated line. 7 In the employment of modern stencil sheets,

I have discovered a process whereby any selected area of theink-impervious coating thereon may be removed so that any desired inkedarea may be printed from the stencil.

Another object of the invention is to provide a process for thesimultaneous removal of a plurality of areas of ink-impervious. coatingfrom a modern stencil sheet,

Another object is to provide a process for the removal of a selectedarea, in contradistinction to lines or dots, of the ink-imperviouscoating of a modern stencil sheet.

Still another object is to provide a process for the simultaneousremoval of a plurality of areas of ink-impervious coating from a modernstencil sheet, the removal requiring substantially less than. twoseconds of time.

Another object is to provide a process whereby the removal of areas ofdifferent sizes of the inkimpervious coating of modern stencil sheetswill leave sharp edges to the de-coated area, rendering the printsresulting from their use, closely resembling standard printing matter.

Another, and important, object of the invention is to provide a processwhereby modern stencil sheets, which have lost their usefulness inmaking ordinary stencils due to hardened coatings, loss of temperingagent, and the like, may be 110 readily employed in making stencils asare fresh stencil sheets.

Yet another object is to provide such a process which may be carried outpractically anywhere and which does not require the use of expensiveapparatus or the employment of highly skilled workmen.

* ment employed to remove an ink-impervious coating from a stencilsheet, as in the improved process.

Figure 2 is a stencil sheet assembly employed in the process, showingthe ink-impervious coating thereof removed by the instrument shown inFigure 1.

Figure 3 is a fragmentary view of a backing sheet forming a part of thestencil sheet assembly.

Figure 4 is a perspective view of another instrument employed forremoving the ink-impervious coating from a modern stencil sheet,employed in the improved process.

Figure 5 is a view substantially on the line 5--5 of Figure 4 with thefragments of a stencil'sheet assembly beneath, shown in cross section.

Figure 6 is a view similar to Figure 5 but show- .ing an imperforateinstrument employed in the process, having a contact surface ofparticularly large area, applied to a stencil sheet and cushioningmaterial shown in cross section.

In the drawings, wherein similar reference characters designatecorresponding parts thruout the several views, the letter A designatesone instrument employed in the process, the letter B a modern stencilsheet, the letter C a second instrument employed in the process, theletter D a handle for the instruments A and C, and the letter E acushioning means.

As for the instrument A, the same is preferably of copper or brass or asuitable substance which will not melt if subjected to a temperature of650 to 900 Fahrenheit. This includes a preferably solid base 10 aboutone quarter inch thick, and provided with a raised contact face bearingsuitable delineations or indicia 11 which are preferably raised betweenand A," from the surface of the base 10. Thus it will be seen thatordinary printers type or electro-type will not be applicable for usefor the removal of the inkimpervious coating of the modern stencilsheet, since printers type generally are of lead (which becomes soft atabout 600 Fahrenheit and this metal is not a good conductor of heat) andelectrotypes of copper plated lead (which were found unsatisfactorysince the lead commences to ooze from the back of the face of theelectro-type upon heating about 600 Fahrenheit and applying slightpressure). These instruments A may be cast or engraved. However, itshould be understood that the instrument employed need not be limited toa solid one since a suitable electric resistance unit might beincorporated therein for the purpose of properly heating the same, theheating of instruments adapted to transmit heat by incorporating thereina heating unit being well known.

The stencil sheet B includes a base 15 of any suitable ink-perviousmaterial such as Yoshino paper, coated or impregnated with a suitableinkimpervious composition of matter such as a eellulose ester and asuitable solvent, requiring a temperature of at least 650 Fahrenheit toremove in order to render the stencil sheet inkpervious over the lines,dots and large areas exposed by removal of the ink-impervious coating.Usually an ink-pervious tempering agent such as castor oil is providedand forms withthe cellulose ester and its solvent a homogeneous body.Ordinarily this covers or impregnates the whole of the base. This baseis generally suitably secured at one end to'a backing sheet 16 usuallyof oiled paper.

The instrument C is provided where large wide or unbroken areas ofink-impervious coatings are to be removed from a stencil sheet, andincludes a base 20 about A" thick and provided with a raised contactface bearing suitable indicia or delineations 21 preferably raisedbetween 3%" and A;" from the surface of the base 20. Spaced aboutone-half inch apart over the area of the face are a plurality ofperforations 22 extending thru the base 20 and opening into the outersurface of the base. Since this instrument C will be subjected totemperatures as high as that of the instrument A, it will be made ofpreferably brass or copper, cast or engraved.

The handle D may be of any suitable material which does not readilyconduct heat and includes a shank 30 ending in a knob 31 and ispreferably detachable from the instruments- A and C. v

The cushioning means E may be any fairly porous material, such asseveral sheets of uncoated Yoshino paper, silk and the like. What isrequired is a material which, when placed be- I tween the base 15 andbacking sheet 16 will permit' gas and air or vapor to pass thru andaround the cushioning means and be dissipated.

In carrying out the process, where an ink-impervious coated orimpregnated modern stencil sheet is employed, the stencil sheet with thebacking sheet beneath is laid upon any suitable flat surface and asuitable instrument such as A is heated to a temperature at or above 650Fahrenheit and laid upon the stencil sheet with the surface of the areaof the instrument bearing the delineations in contact with the stencilsheet. If the sheet is a fresh one, with a considerable quantity of thetempering agentstill in the mixture, the heated instrument should remainabout only one second and then removed by a movement at a right angle tothe surface of the stencil sheet. It is important that the instrumentnot be moved laterally after it is in contact with the sheet. Nopressure upon the instrument A is required and the instrument is ofcourse applied and removed by the operator grasping the handle D.

Upon removal of the instrument, it will be found that the ink-imperviouscoating has been removed from the stencil sheet over an areacorresponding to the raised face area of the instrument A as shown inFigure 2, the lines being sharp and the area being clean and welldefined. The ink-pervious tempering agent will be found to betemporarily liquefied but this interferes in no way with the subsequentuse of the stencil sheet since it has been found that this liquefiedtempering agent may be either wiped 'off, allowed to evaporate or againharden. de-

up similarly to Figure 2 with the lettering colorbe at once used. Thebase will be found uncharred and while the backing sheet may have afaint delineation thereon as shown in Figure 3, this is but due to theheat affecting the oil in the backing sheet and does not interfere withthe process. In fact, it has been found that the ba :king sheet may bedispensed with and the stencil sheet, minus its backing sheet, placedupon even a glass base and the process carried out as outlined above.

Upon removal of the instrument A, a film of the residue of theink-impervious coating having physical and chemical characteristicsdifferent from the coating will be found upon theface of the instrumentA. This film may be readily removed by the employment of a suitablescouring composition made into a paste, rubbed over the face of theinstrument A, and then washed off.

If desired, the stencil sheet may now be further stenciled in atypewriter or the like.

However, the process is equally as applicable to modern stencil sheetswhich have deteriorated, due to loss of the tempering agent, and areconsequently otherwise unusable. The ink-impervious coating on thesesheets may be removed as outlined above, but the heated instrumentshould be applied for a shorter period,--approximately one second. Thiswill remove the coating where desired but will not char the base. Thusit will be seen that the value of the tempering agent insofai as thisprocess is concerned-is negligible.

It has been found that where a solid area, above a half inch square, isto be de-coated as outlined above, it is desirable to provide some meansfor a plentiful supply of heated oxygen from the air to come intocontact with the area to be de-coated as well as to provide means forthe escape of entrapped gases, vapor, air or the like which may collectbetween the instrument and the stencil sheet and which are. liable tocause the instrument to slip over the stencil sheet, since some littlepressure on the instrument is desirable in de-coating large areas. For

this reason, the perforated instrument C is employed, the entrappedgases and vapor arising from the action of the heat upon the substancescomprising the stencil sheet passing off thru the perforations while theoxygen of the air will have access to the coating thru the perforations.

As an altemative'for the perforated instrument C, the instrument A maybe employed, having a large face area to be used, and the cushioningmeans E used in conjunction therewith, between the base 15 and backingsheet 16. The entrapped air, gases and vapor will then pass off and thruand about the cushioning means and the oxygen of the air will also beable to reach the coating thru the cushioning means E and base 15.

It is sometimes desirable to have a stencil which may be used to printcolorless indicia upon a colored background. For that purpose, theprocess embraces employing an ink-pervious base such as Yoshino paper,and coating printers type, or any suitable device having the desiredindicia thereon, with a suitable ink-impervious coating such aspyroxylin enamel and then transferring the coating to the base byapplying the device to the base. As an example, the raised base of theinstrument A might be coated with a plastic inkimpervious pyroxylineenamel and at once the coating transferred to a sheet of Yoshino paperwhere it would appear as shown in Figure 3. Then the print resultingtherefrom would show less and the background suitably colored.

By the employment of this process, stencils may be'provided in only afraction of the time necessary to scribe the same by the employment of astylus, stencils may be provided having large de-coated areas and notmerely dotted or lined areas, and by the process the areas will besharply defined.

Various-changes in the steps of the process herein described, may bemade without departing from the spirit of the invention or the scope ofthe claims.

What is claimed is:

1. Those steps in the process of making a stencil from a stencil sheetcarryingan adhering inkimpervious cellulose ester, which consists inbringing an instrument in contact therewith, heated to at least 650Fahrenheit, causing substantially all of said cellulose ester in contactwith said] instrument to be changed physically and chemically, andremoving the instrument.

2. Those steps in the process of making a stencil from a stencil sheethaving a coating including a cellulose compound, which consists inbringing an instrument in contact therewith, heated to at least 650Fahrenheit, causing substantially all of said cellulose compound incontact with said instrument to change its physical and chemicalcharacteristics, and removing the instrument. v

3. Those steps in the process of making a stencil from a stencil sheethaving a coating including pyroxylin enamel, which consists in bringingan instrument in contact with said enamel, heated to at least 650Fahrenheit, causing substantially all of said enamel in contact withsaid instrument to change its chemical and physical characteristics andremoving the instrument.

4. Those steps in the process of making a stencil from a stencil sheethaving a coating including an ink-impervious substance requiring a heatabove that of the melting point of paraffin for its removal byoxidation, which consists in bringing an instrument in contacttherewith, heated to a temperature above the temperature of the meltingpoint heat of paraffin, and in the presence of air, causing oxidation ofsaid substance by the oxygen of the air while in the presence of theheat of said instrument and removing the instrument.

5. Those steps in the process of making a relatively large, solid areaink-pervious on a stencil sheet having an ink-impervious coating, whichconsists in laying a heated instrument thereon,

its

with a relatively large solid contact area of said I change itscharacteristics and adhere in part to said instrument, causingsubstantially the balance of said ink-impervious coating under said areato change its characteristics and dissipate to the atmosphere, andremoving the instrument.

6. Those steps. in the process of rendering a relatively large solidarea ink-pervious on'a stencil sheet having an ink-impervious coating,which consists in laying. a heated instrument thereon, with the surfacearea of said instrument in contact with said stencil sheet relativelylarge and solid, causing a portion of the coating residue resulting fromsaid step to change its physical and chemical characteristics and adhereto said instrument and removing the instrument, the heat of saidinstrument being such that a portion of the residue of said coating incontact with said contact area of said instrument will come away uponsaid instrument.

7. Those steps in the process of simultaneously rendering a plurality ofrelatively large solid areas ink-pervious on a stencil sheet having anink-impervious coating, which consists in laying a heated instrumentthereon, with the surface areas of said instrument in contact with saidstencil sheet relatively large and solid, causing a portion of thecoating residue resulting from said step to change its physical andchemical properties and dissipate to the atmosphere, and removing saidinstrument.

8. Those steps in the process of making a stencil from a stencil sheetincluding a base carrying an adhering ink-impervious composition ofmatter, which consists in heating an instrument to a temperaturenecessary to cause oxidation of said composition of matter, applyingsaid heated instrument to said sheet in the presence of the oxygen ofthe air, permitting the oxygen of the air to reach said coatingthru saidinstrument and the gaseous products arising from the action of theoxygen and heat upon the composition of matter to pass off thru saidinstrument, and removing the instrument before it chemically affectssaid base.

9. Those steps in the process of de-coating a relatively large solidarea of a stencil sheet having a base coated with an ink-imperviouscoating, and with an ink-pervious tempering agent, which consists inheating an instrument to a temperature necessary to promote oxidation ofsaid inkimpervious coating, applying said instrument to said coating inthe presence of the oxygen of the air with the surface area of saidinstrument in contact with said coating relatively large and solid,permitting air to pass thru said instrument to said coating and thegaseous products arising from the action of the oxygen of the air uponthe ink-impervious coating to pass off thru said instrument, andremoving the instrument with substantially the remainder of saidoxidized coating thereon.

10. Those steps in the process of de-coating a relatively large solidarea of a stencil sheet having a base coated with an ink-imperviouscoating, which consists in heating an instrument to a temperaturenecessary to promote oxidation of said ink-impervious coating, applyingsaid instrument to said coating in the presence of the oxygen of the airwith the surface area of said instrument in contact with said coatingrelatively large and solid, permitting air to pass thru said instrumentto said coating the gaseous products arising from the oxygen of the airand the action of the heat upon the ink-impervious coating to pass thrusaid instrument, and removing the instrument with substantially all ofthe remainder of said oxidized coating thereon.

11. Those steps in the process of making a stencil from a stencil sheethaving a porous base carrying an adhering ink-impervious composi--' tionof matter, which consists in cushioning said stencil sheet upon arelatively flat porous cushion in the presence of the oxygen of the air,heating an instrument to a temperature necessary to promote oxidation ofsaid composition of matter, ap-

plying said instrument to said stencil sheet, permitting the gaseousproducts arising from the action of the heat and oxygen of the air uponthe composition of matter to pass ofi thru said cushion, and removingthe instrument. I

12. Those steps in the process of making a stencil from a stencil sheethaving a porous paper base carrying an adhering impervious compositionof matter and an ink-pervious tempering agent, which consists incushioning said stencil sheet upon a relatively fiat porous cushion,adapted to permit the circulation of air and gases therethru, heating aninstrument to a temperature necessary to promote oxidation of saidcomposition of matter, applying said instrument to said stencil sheet inthe presence of the oxygen of the air, permitting the gaseous productsarising from the action of the heat and oxygen of the air upon thecomposition of matter and tempering agent to circulate thru saidcushion, and removing the instrument.

PHILIP H. MURPHY.

